DESCRIPTION: (Applicant's Abstract) The Correction of Myopia Evaluation Trial (COMET) is a multi-center, randomized, double-masked clinical trial designed to assess whether progressive addition lenses (PAL's) slow the progression of juvenile-onset myopia, as compared to conventional single vision lenses (SV). Four participating clinical centers, at Colleges of Optometry in Boston, Birmingham, Philadelphia, and Houston, will enroll a study total of 450 children with myopia (-1.25 D to -4.5 D) in both eyes, 6-12 years old, who meet specific inclusion and exclusion criteria. They will be identified primarily from elementary school vision screenings and College of Optometry clinical patient records. All eligible children will be examined at baseline and at six-month intervals for at least three years to measure changes in refractive error and to update prescriptions. A standardized, common protocol will be used at all centers. The primary outcome measure is progression of myopia, as measured by cycloplegic autorefraction. An additional outcome measure is axial elongation as measured by A-scan ultrasonography. These will be obtained by masked examiners. In addition to presenting the COMET study in general, this application seeks support for the Study Chair's Office at the New England College of Optometry. Complete details of the COMET rationale, design, and methods are contained in the attached Manual of Procedures. Resource centers for the COMET are the Study Chair's Office in Boston, MA, and the Coordinating Center in Stony Brook, NY.